1 WWW.GOFLY.ONLINE Y ONLI NE FLI GHT SCHOOL Chapter 1 PRINCIPLES OF FLIGHT Aerodynamics Terminology Aerofoil An aerofoil is the cross sectional shape of an aircraft wing. Span The span is the distance from one wingtip to the other. Chord The chord line is a line joining the leading and trailing edge in a straight line. Camber Camber refers to the curvature or convex shape of the wing’s aerofoil section. Thickness The thickness of an aerofoil is the maximum distance between the upper and lower surfaces. Chord ratio The chord ratio is defined as the ratio of the wing’s chord length (the distance between the leading and trailing edges of the wing) to its wingspan (the distance from one wingtip to the other). Relative airflow The relative airflow is airflow, having both speed and direction, that moves over an aerofoil. Angle of attack The angle of attack is the angle between the chord line and the relative airflow. Total reaction force Lift is a force that acts at right angles to the relative airflow while drag acts in the opposite direction of the relative airflow. The resultant force considering the lift, and the drag, is the total reaction force. Lift Lift is a force, acting perpendicular to the chord of the aerofoil, generated as air flows over an aerofoil. Drag Drag is the force that opposes the movement of an aircraft through the air. Design Features/Controls Consider the purpose of the following design features/controls. Dihedral Dihedral is the upward angle of the aircraft’s wings from the wing root to the wing tip. Having the wings designed with an upward angle makes the aircraft more stable. If the wings had no dihedral then the aircraft would continue to bank until the pilot corrected the bank. Aspect ratio Aspect ratio refers to the ratio of the length versus the width of an aircraft wing. A short wide wing has a low aspect ratio, while a long thin wing has a high aspect ratio. Sweepback Sweepback is the angle of the wing as it slopes back from the aircraft fuselage. Higher performance aircraft usually have swept wings as they create less drag at higher speeds.
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